Industrial processing surfaces, including scrubbers, are conventionally treated using clean-in-place (CIP) methods to provide flushing, rinsing, pretreatment, cleaning, disinfecting, sanitizing and preserving, in order to prevent fouling during processing. Fouling components and deposits can include inorganic salts, particulates, microbials and organics. Fouling manifests itself as a decline in performance and/or quality of the finished goods. Fouling can also include biofilm growth along with other impurities within industrial processing systems, such as CO2 scrubbers employed in ethanol and other fermentation systems, having detrimental results. As a result, CIP processes are utilized to circulate cleaning agents over and through the industrial processing surfaces to wet, penetrate, dissolve and/or rinse away foreign materials. Various parameters that can be manipulated for cleaning typically include time, temperature, mechanical energy, chemical composition, chemical concentration, soil type, water type, and hydraulic design. Conventional cleaning techniques include the use of high heat and/or extreme pH, i.e., very high alkalinity use solutions, or very low pH acidic use solutions. However, many surfaces cannot tolerate such conditions.
In an exemplary industrial processing, CO2 scrubbers are often used to remove impurities such as aldehydes and alcohols from the industrial effluent by spraying water through a column packed with porous spheres of HDPE plastic to improve surface contact. However, over time, biofilms form inside the scrubbers, causing plugging, fouling, reduction of optimal flow, and potential contamination of the upstream process in cases where ethanol (EtOH) is reclaimed back into the process that has been carried out with the CO2. Such biofilm growth and impurities, such as aldehydes and alcohols, need to be removed from industrial surfaces to prevent severe decline in production and operation of the systems which can also negatively impact the quality of finished goods, and often premature replacement of such industrial processing systems.
Among various biocides known, peroxycarboxylic acids are increasingly used as antimicrobials and bleaching agents in many applications, owing to their high efficacy against a broad spectrum of microorganisms, color safe property, low residues and nontoxic nature of their decomposition products. Peracetic acid is the most commonly used peroxycarboxylic acid and has been shown to be a good biocide, but only at relatively high concentrations (generally greater than 80 part per million). Similarly, peroxyfatty acids have also been shown to be biocidal, but only at high concentrations (greater than 200 ppm), such as in the composition disclosed in European Patent Application No. 233,731. In contrast, peroxyformic acid has an advantageous degree and range of microcidal properties compared to other peroxycarboxylic acids, such as peracetic and perproprionic acids, as disclosed by V. Merka et al in J. Hyg. Epidem. Microbiol. Immunol, 1965 (IX) 220, as well as in European Patent Application No. 863,098,96.
Although various agents preventing microbial growth, such as oxidizers and biocides, are known for cleaning industrial processing surfaces, including CIP cleaning techniques, there is still a need for an improved method for the prevention of microbial growth and biofilm formation.
Biofilms are biological conglomerates that contain pathogens, such as bacteria and other microorganisms, embedded in a matrix of exopolymers and macromolecules. In addition to bacteria, other microorganisms are commonly found in biofilm, including fungi, molds, algae, protozoa, archaea and mixtures of these microorganisms. Biofilms form as a result of microorganisms establishing on a surface and producing a protective extracellular polymeric matrix. Most often biofilm form on surfaces in contact with water, providing a hydrated matrix of polysaccharides to provide structural protection from biocides, making biofilm more difficult to kill than other pathogens.
Microbial infection and the formation of biofilm present significant complications in numerous industries. Although biofilm are known to exist in a wide-variety of environmental conditions, since biofilm most often form on surfaces exposed to bacteria and water, industries such as food processing are commonly affected by biofilm. For example, the organism Listeria monocytogenes thrives in cool, damp environments, such as floor drains, plumbing and other surfaces of food processing facilities. This provides a potential point of contamination for a processing plant environment and food products produced therein. However, biofilm can also develop on inert surfaces of everyday household items. Exposure to such microorganisms through skin-surface contact may result in infections and compromise the public's health. Therefore, controlling the formation of biofilm is desirable to decrease exposure to infectious microorganisms.
Biofilm growth and removal depends on several factors, including the surface composition and chemical composition of the surrounding environment. Several biofilm removal methods are utilized, including physical, chemical and biological removal. Means of physically removing biofilm include the use of magnetic fields, ultra sound, high and low electrical fields and abrasive techniques. Physical removal techniques are often combined with chemical or biological methods, such as biocides or antimicrobial agents. A number of technologies have been developed that treat surfaces with organic or inorganic materials to interfere with biofilm development, such as preventing microbial attack and degradation. For example, coating a surface with or incorporating a composition into a surface substrate to create a surface wherein microorganisms do not adhere or colonize. U.S. Pat. No. 9,072,292. However, such technologies have not effectively eliminated biofilm formation and growth. Therefore, the contamination of surfaces with biofilm remains a problem.
In light of the foregoing, there remains a demand for compositions and methods for reducing and removing biofilm.
Accordingly, it is an objective of the claimed invention to provide peroxyformic acid compositions, including those which can be generated in situ for the prevention and removal of microbial growth and biofouling from industrial processing surfaces, including CO2 scrubbers.
Other objects, advantages and features of the present invention will become apparent from the following specification taken in conjunction with the accompanying drawings.